Lasers
Refer to Laser Specifications and the laser safety sections in the preface of this manual for further information.
Primary Shutter
As part of the laser safety system, a primary shutter is incorporated that interrupts the output beam prior to the output coupler(s). This mechanism blocks the beam when the Interlock circuit is opened or when the key is in the off position. The primary shutter opens to allow the combined laser beam to be emitted when the interlock circuit is restored as described in Remote Interlock.
Laser Intensity Control
The laser output power is controlled from software via the USB or RS-232 serial communications interfaces.
Laser On/Off Control
Only 1 or 2 wavelengths are allowed by software to be on at any one time for any High Power Laser Engine unit. In dual-High Power Laser Engine configuration, this means that up to 4 lasers can be on.
The lasers can be turned on and off from software over the USB or RS-232 serial communications interfaces, and in addition can be quickly turned on and off via signals on the TTL Interfaces (Programmable TTL Input BNC and TTL Control Port D-sub connectors). The Programmable TTL Input BNC is used for Laser Blanking (see below), whereas the TTL Control Port has on/off control for individual lasers. The response times are shown in the table below.
On/off speed restrictions for a range of laser types.
| Laser | Description |
|---|---|
| Most |
≤ 20 μs rise/fall times |
|
LM- LM- |
≤ 10 μs rise/fall times |
|
HLE-FL1 Fibre Lasers (LM-HLE-560-1000, LM-HLE-594-1000 & LM-HLE-642-1000) |
Maximum recommended shutters speed 10 Hz continuous operation, 20 Hz for operation up to 10 minutes. |
Only the HLE-FL1 Fibre Lasers are at risk of damage if driven faster than the recommended speed above; the other lasers will be fine.
Laser Blanking
The standard configuration of the High Power Laser Engine allows the lasers to be blanked (turned off) in response to a “Fire” signal from one or more cameras, or other devices. This is to allow the lasers to only be on when required, esp. to avoid specimen damage or fluorophore bleaching.
Laser blanking uses the Programmable TTL Input BNC (Programmable TTL Input/Output), which functions as follows:
-
The blanking input requires the camera “Fire” signal to be a TTL high when the camera is exposing and a TTL low during readout (not exposing).
-
The High Power Laser Engine will turn on all lasers enabled in software when the input is high and blank the laser outputs when the signal is low.
-
The BNC input is internally pulled high in the absence of a signal input so that the High Power Laser Engine will always be in expose mode if no camera fire signal is connected.